South Korean shares fell to their lowest level in a year Wednesday, extending their losing streak to a fourth day, as investors' concerns grew over policy uncertainties under the incoming US Trump administration.

The local currency also dropped against the US dollar to a two-year low, breaching 1,400 won for the second straight session as of 3:30 p.m.

The benchmark Korea Composite Stock Price Index sank 65.49 points, or 2.64 percent, to close at 2,417.08, marking the lowest since Nov. 13, 2023, when the index closed at 2,403.76.

Trade volume was moderate at 605 million shares worth 10.8 trillion won ($7.6 billion), with losers far outpacing winners 801 to 104.

Foreigners sold a net 711 billion won worth of local stocks, and individuals bought a net 650 billion won. Institutions bought a net 18.7 billion won.

Investors' sentiment was dampened, with exporters, such as Samsung Electronics and POSCO, coming under heavy sell-offs.

The weak Korean won also adding downward pressure to the market, which investors fear would accelerate foreign capital flight.

"The domestic market is in a slump due to the strong US dollar and a rise in government bond yields," Kim Ji-won, a researcher at KB Securities, said.

Top market cap Samsung Electronics plunged 4.53 percent to 50,600 won, the lowest closing in more than four years amid lingering concerns over its business competitiveness in the chip market.

Carmakers also finished bearish, with industry leader Hyundai Motor falling 3.43 percent and its sister Kia losing 1.2 percent.

Steelmakers closed lower as well, with Posco Holdings sinking 5.25 percent and Korea Zinc sliding 14.1 percent.

The local currency was trading at 1,406.6 won against the greenback at 3:30 p.m., down 3.1 won from the previous session's close.

The Korean won has been hovering around the psychologically significant 1,400 against the US dollar, following Trump's victory in the US presidential election last week.

The Korean financial market, meanwhile, will open at 10 a.m., one hour later than usual, on Thursday due to the national college entrance exam. (Yonhap)